Passenger assist straps comprised of thermoplastic, webbing, fabric, leather or a combination of these, are installed within many public transit vehicles, namely buses, subways/metros and passenger trains. The passenger assist straps are traditionally installed on the horizontal overhead stanchions that run parallel to the aisle ways. Passengers can grasp the passenger assist straps to steady themselves while standing within the public transit vehicle.
In some cases, the strap will be folded in such a way as to create a top loop which will encircle the horizontal overhead handrail, and a bottom loop which passengers can grasp. The passenger assist strap can be held together with a clamp or buckle located at a portion of the assist strap between the top and bottom loops where there are typically three layers of strap material, the front strap, back strap and a middle strap portion since the front or back strap overlaps itself.
FIG. 1 shows a prior art clamp 10 which consists of two pieces which together are clamped onto a loop of strap with a machine screw, thus creating a top loop and bottom loop. As the machine screw is tightened, the two pieces of the clamp squeeze together onto the strap to keep the top and bottom loops intact. The sides of the front and back layers of the strap material may be partially covered by the sides of the clamp pieces, but the third middle layer will not be covered, so that the side of the first piece will not meet the side of the second piece of the clamp. This is advantageous since the clamp will not “bottom out” while being tightened in that the sides of the clamp pieces will not meet and therefore restrict the clamp from being further tightened onto the assist strap.
However, a disadvantage is that the machine screw can become loose, either through vibrations or tampering and the result is that the two pieces of the clamp can twist and become misaligned. This can cause damage or premature wear to the assist strap. Also, as the two pieces twist and misalign, they may contribute to the machine screw becoming even looser. Under these conditions, the machine screw can become so loose that the clamp will become completely disengaged. This in turn causes the top loop to become disengaged from the horizontal handrail to which the assist strap is installed and can lead to passenger injury if a passenger is holding onto the strap at such time and relying on its assistance.